Apparatus to establish wireless backhaul connection

ABSTRACT

Provided is an apparatus including: an acquisition unit configured to acquire information indicating one or more second base stations located within coverage of a first base station connected to a wired backhaul; and a controller configured to control establishment of a wireless backhaul between the first base station and each of the one or more second base stations.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 15/517,948, filed Apr. 7, 2017, which is a NationalStage of PCT/JP2015/077218, filed Sep. 25, 2015, and claims the benefitof priority from prior Japanese Patent Application JP 2014-212630, filedOct. 17, 2014. Each of the above-referenced applications is herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to an apparatus.

BACKGROUND ART

In 2002, the mobile phone service of the 3G system, called the thirdgeneration, started in Japan. At first, small-size packets were used fortransmission or reception to perform voice calls and mail transmission.However, with the introduction of high-speed downlink packet access(HSDPA), it became possible to transmit and receive larger-size packetsfor downloading of music files or streaming of video. With such anincrease in packet capacities, the service of long term evolution (LTE)in which orthogonal frequency division multiple access (OFDMA) is usedon the downlink also started for the expansion on the side of thewireless network. In addition, the launch of 4G services is scheduled tobe made around 2015. Accordingly, up to one gigabit per second (Gbps)will be achieved in a semi-fixed environment and up to 100 Mbps will beachieved even in a mobile environment.

With such increase in network traffic, it is desirable to arrange asmall base station that is inexpensive and easy to install forpreventing the concentration of traffic. Various techniques aredeveloped for such a small cell.

In one example, Patent Literature 1 discloses the technique forselecting a device that operates as an access point for a mobile stationbased on the quality obtained by measuring a wireless signal transmittedfrom one or more terminal devices.

CITATION LIST Patent Literature

Patent Literature 1: WO 2014/034255

DISCLOSURE OF INVENTION Technical Problem

The hot spot of traffic can change dynamically, and accordingly thelocation where small cells are preferably arranged can change. In oneexample, it is also conceivable to arrange a large number of small cellsin advance. However, arranging a large number of small cells andconnecting a base station of each small cell to a wired backhaul can bea heavy burden on the operator.

Therefore, it is desirable to provide a mechanism for enabling flexiblearrangement of cells with a smaller burden.

Solution to Problem

According to the present disclosure, there is provided an apparatusconfigured to include an acquisition unit and a controller. Theacquisition unit configured to acquire information indicating one ormore second base stations located within coverage of a first basestation connected to a wired backhaul, and the controller is configuredto control the establishment of a wireless backhaul between the firstbase station and each of the one or more second base stations.

Advantageous Effects of Invention

According to the present disclosure as described above, it is possibleto perform flexible arrangement of cells with a smaller burden. Notethat the effects described above are not necessarily limitative. Inconjunction with or in place of the above effects, there may be achievedany one of the effects described in this specification or other effectsthat may be construed from this specification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrated to describe an exemplary schematicconfiguration of a system according to an embodiment of the presentdisclosure.

FIG. 2 is a block diagram illustrating an exemplary configuration of afirst base station according to the present embodiment.

FIG. 3 is a block diagram illustrating an exemplary configuration of acontrol device according to the present embodiment.

FIG. 4 is a diagram illustrated to describe an example of grouping of aplurality of second base stations.

FIG. 5 is a diagram illustrated to describe an example of grouping basedon information relating to position.

FIG. 6 is a diagram illustrated to describe an example of grouping basedon information relating to traffic.

FIG. 7 is a diagram illustrated to describe an example of a referencesignal in a case of two layers.

FIG. 8 is a diagram illustrated to describe a first example of asubframe allocated to each group.

FIG. 9 is a diagram illustrated to describe a second example of asubframe allocated to each group.

FIG. 10 is a diagram illustrated to describe a first example ofallocation of an antenna element to each of the second base stations.

FIG. 11 is a diagram illustrated to describe a second example ofallocation of an antenna element to each of the second base stations.

FIG. 12 is a diagram illustrated to describe a third example ofallocation of an antenna element to each of the second base stations.

FIG. 13 is a diagram illustrated to describe an example of a case wherethere is no allocation of an antenna element to the second base station.

FIG. 14 is a sequence diagram illustrating an example of a schematicprocedure of processing according to a first embodiment.

FIG. 15 is a sequence diagram illustrating an example of a schematicprocedure of processing according to a second embodiment.

FIG. 16 is a block diagram illustrating an exemplary schematicconfiguration of a server.

FIG. 17 is a block diagram illustrating a first example of a schematicconfiguration of eNB.

FIG. 18 is a block diagram illustrating a second example of a schematicconfiguration of eNB.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, (a) preferred embodiment(s) of the present disclosure willbe described in detail with reference to the appended drawings. In thisspecification and the appended drawings, constituent elements that havesubstantially the same function and structure are denoted with the samereference numerals, and a repeated description of these constituentelements is omitted.

In the specification and drawings, components having substantiallyidentical functional structure are sometimes distinguished by appendingdifferent alphabet characters following identical reference numerals. Inone example, a plurality of components having substantially identicalfunctional structure are distinguished from each other in a similar wayto second base stations 20A, 20B, and 20C, as necessary. However,identical reference numerals are appended to a case where there is noparticular significance to distinguish between a plurality of componentshaving substantially identical functional structure. In one example, inthe case where there is no particular significance to distinguishbetween second base stations 20A, 20B, and 20C, they are simply referredto as second base station 20.

The description will be given in the following order.

1. Schematic Configuration of System

2. Configuration of each Device

2.1. Configuration of First Base Station 2.2. Configuration of ControlDevice 3. First Embodiment 3.1. Technical Features 3.2. ProcessingProcedure 4. Second Embodiment 4.1. Technical Features 4.2. ProcessingProcedure 5. Application Examples 5.1. Application Example for ControlDevice 5.2. Application Example for First Base Station 6. Brief Summary<<1. Schematic Configuration of System>>

A schematic configuration of a system 1 according to an embodiment ofthe present disclosure is now described with reference to FIG. 1. FIG. 1is a diagram illustrated to describe an exemplary schematicconfiguration of the system 1 according to an embodiment of the presentdisclosure. Referring to FIG. 1, the system 1 includes a first basestation 100, a second base station 20, a terminal device 30, and acontrol device 200.

(First Base Station 100)

The first base station 100 performs wireless communication with theterminal device 30 located within its own coverage 10. The first basestation 100 is connected to a wired backhaul 40. In one example, thefirst base station 100 is a macrocell base station, and the coverage 10is a macrocell.

In the embodiment of the present disclosure, the first base station 100also performs wireless communication with the second base station 20located within the coverage 10. In particular, the first base station100 provides a wireless backhaul for the second base station 20. In oneexample, the first base station 100 performs wireless communication withthe second base station 20 using a frequency band that is different froma frequency band used for wireless communication with the terminaldevice 30. Alternatively, the first base station 100 may performwireless communication with the second base station 20 using the samefrequency band as the frequency band that is used for wirelesscommunication with the terminal device 30.

(Second Base Station 20)

The second base station 20 performs wireless communication with theterminal device 30 located within its own coverage 21. The second basestation 20 has no connection with a wired backhaul. In one example, thesecond base station 20 is a small base station, and the coverage 21 is asmall cell. The small cell may also be referred to as microcell,picocell, or femtocell.

In the embodiment of the present disclosure, the second base station 20also performs wireless communication with the first base station 100. Inparticular, the second base station 20 performs communication throughthe wireless backhaul provided by the first base station 100.

In one example, the second base station 20 is a wireless communicationdevice having a first operation mode for operating as a mobile stationand a second operation mode for operating as a base station.

In another example, the second base station 20 may only operate as abase station, not a mobile station. The second base station 20 mayoperate in a first operation mode for performing wireless communicationwith the terminal device 30 and a second operation mode for stoppingwireless communication with the terminal device 30. The second operationmode may be referred to as an off mode, a sleep mode, a standby mode, orthe like. The second base station 20 may be a stationary base station.

Moreover, the second base station 20 is an independent base stationrather than a relay station. In one example, the second base station 20has its own retransmission control function. More specifically, in oneexample, the second base station 20 executes the HARQ process.

(Terminal Device 30)

The terminal device 30 performs wireless communication with a basestation. In one example, the terminal device 30, which is located withinthe coverage of the first base station 100, performs wirelesscommunication with the first base station 100. In one example, theterminal device 30, which is located within the coverage of the secondbase station 20, performs wireless communication with the second basestation 20.

(Control Device 200)

The control device 200 may control the first base station 100. In oneexample, the control device 200 may control a plurality of first basestations 100.

<<2. Configuration of Each Device>>

An exemplary configuration of the first base station 100 and the controldevice 200 according to the embodiment of the present disclosure is nowdescribed with reference to FIGS. 2 and 3.

<2.1. Configuration of First Base Station>

An exemplary configuration of the first base station 100 according tothe embodiment of the present disclosure is now described with referenceto FIG. 2. FIG. 2 is a block diagram illustrating an exemplaryconfiguration of the first base station 100 according to the embodimentof the present disclosure. Referring to FIG. 2, the first base station100 is configured to include an antenna unit 110, a wirelesscommunication unit 120, a network communication unit 130, a storage unit140, and a processing unit 150.

(Antenna Unit 110)

The antenna unit 110 radiates a signal outputted from the wirelesscommunication unit 120 into space as a radio wave. In addition, theantenna unit 110 converts a radio wave in space to a signal and outputsthe signal to the wireless communication unit 120.

(Wireless Communication Unit 120)

The wireless communication unit 120 transmits and receives a signal. Inone example, the wireless communication unit 120 transmits a downlinksignal to the terminal device 30 located within the coverage 10 andreceives an uplink signal from the terminal device 30 located within thecoverage 10. In one example, the wireless communication unit 120transmits a signal to the second base station 20 located within thecoverage 10 and receives a signal from the second base station 20located within the coverage 10.

(Network Communication Unit 130)

The network communication unit 130 transmits and receives informationthrough the wired backhaul 40. In one example, the network communicationunit 130 transmits information to another node through the wiredbackhaul 40 and receives information from the other node. An example ofthe other node includes a core network node (e.g., a serving gateway(S-GW) and a mobility management node (MME)). The other node may furtherinclude a control device 200.

(Storage Unit 140)

The storage unit 140 temporarily or permanently stores a program anddata necessary for the first base station 100 to operate.

(Processing Unit 150)

The processing unit 150 enables the first base station 100 to performvarious functions. The processing unit 150 is configured to include aselector 151, a grouping unit 153, an information acquisition unit 155,and a controller 157. Moreover, the processing unit 150 may furtherinclude a component other than these components. In other words, theprocessing unit 150 may also perform an operation other than operationsof these components.

A detailed description of operations of the selector 151, the groupingunit 153, the information acquisition unit 155, and the controller 157will be given later.

<2.2. Configuration of Control Device>

An exemplary configuration of the control device 200 according to theembodiment of the present disclosure is now described with reference toFIG. 3. FIG. 3 is a block diagram illustrating an exemplaryconfiguration of the control device 200 according to the embodiment ofthe present disclosure. Referring to FIG. 3, the control device 200 isconfigured to include a communication unit 210, a storage unit 220, anda processing unit 230.

(Communication Unit 210)

The communication unit 210 transmits and receives information. In oneexample, the communication unit 210 transmits information to anothernode and receives information from the other node. An example of theother node includes the first base station 100.

(Storage Unit 220)

The storage unit 220 temporarily or permanently stores a program anddata necessary for the control device 200 to operate.

(Processing Unit 230)

The processing unit 230 enables the control device 200 to performvarious functions. The processing unit 230 is configured to include aselector 231, a grouping unit 233, an information acquisition unit 235,and a controller 237. Moreover, the processing unit 230 may furtherinclude a component other than these components. In other words, theprocessing unit 230 may also perform an operation other than operationsof these components.

A detailed description of operations of the selector 231, the groupingunit 233, the information acquisition unit 235, and the controller 237will be given later.

<<3. First Embodiment>>

A first embodiment of the present disclosure is described with referenceto FIGS. 4 to 14.

<3.1. Technical Features>

Technical features according to the first embodiment are described withreference to FIGS. 4 to 13.

(1) Selection of Second Base Station 20

In one example, the first base station 100 (the selector 151) selectsone or more of the second base stations 20 located within the coverage10 of the first base station 100.

(a) Trigger for Selection

In one example, the first base station 100 (the selector 151) selectsthe one or more second base stations 20 in the case where apredetermined condition on traffic of the first base station 100 issatisfied.

In one example, the predetermined condition is that the traffic volumeof the first base station 100 exceeds a threshold value. In other words,the first base station 100 (the selector 151) selects the one or moresecond base stations 20 in the case where the traffic volume of thefirst base station 100 exceeds the threshold value.

In one example, the first base station 100 (the selector 151) monitorsthe traffic volume in real time or periodically. The traffic may betraffic processed previously by the first base station 100 or traffic tobe processed by the first base station 100. The traffic volume may bethe average value of a traffic volume to be processed by the first basestation within a certain period.

This makes it possible, for example, to enhance the traffic volume thatcan be processed within the coverage 10 with the increase of traffic ofthe first base station 100.

(b) Selection Technique

In one example, the first base station 100 (the selector 151) selectsthe one or more second base stations 20 from among a plurality of secondbase stations 20 located within the coverage 10 of the first basestation 100.

(b-1) Selection Depending on Position and Traffic Volume of TerminalDevice 30

In one example, the first base station 100 (the selector 151) selectsthe one or more second base stations 20 depending on the position andtraffic volume of the terminal device 30 performing wirelesscommunication with the first base station 100. In one example, the oneor more second base stations 20 are base stations that are locatedwithin an area with high traffic density in the coverage 10.

Specifically, in one example, the first base station 100 (the selector151) finds an area with a high traffic volume within the coverage 10from the positions and traffic volumes of the plurality of terminaldevices 30 performing wireless communication with the first base station100. Then, the first base station 100 (the selector 151) selects one ormore second base stations 20 located in the relevant area (or near thearea).

The area may be a sector with high traffic density among two or moresectors included in the coverage 10. Specifically, the first basestation 100 (the selector 151) may calculate the traffic volume of eachof two or more sectors included in the coverage 10. Then, the first basestation 100 (the selector 151) may find a sector with a high trafficvolume (e.g., a sector whose traffic volume exceeds a threshold value)and may select one or more second base stations 20 located in thesector.

(b-2) Information Relating to Second Base Station 20

In one example, the first base station 100 holds information that isrelated to the second base station 20 located within the coverage 10 andselects the one or more second base stations 20 based on theinformation.

Moreover, the information described above can be changed dynamically. Inone example, in the case where a new second base station 20 is locatedwithin the coverage 10, the information may include additionallyinformation relating to the new second base station 20.

As described above, the first base station 100 (the selector 151)selects the one or more second base stations 20. This makes it possible,for example, to arrange cells according to dynamically changing trafficconditions.

(2) Control of Wireless Backhaul Establishment

The first base station 100 (the information acquisition unit 155)acquires information indicating one or more second base stations 20located within the coverage 10 of the first base station 100. The firstbase station 100 (the controller 157) controls the establishment of awireless backhaul between the first base station 100 and each of the oneor more second base stations 20.

(a) One or More Second Base Stations 20

In one example, the one or more second base stations 20 are one or moresecond base stations selected by the selector 151 as described above.The information acquisition unit 155 acquires information indicating oneor more second base stations 20 selected by the selector 151.

(b) Example of Control

In one example, the control of the establishment of the wirelessbackhaul as described above includes performing a procedure forestablishing the wireless backhaul with each of the one or more secondbase stations 20 (hereinafter referred to as “backhaul establishmentprocedure”).

(b-1) Providing Information for Backhaul Establishment

In one example, the backhaul establishment procedure includes providinginformation for establishing a wireless backhaul between the first basestation 100 and the second base station 20 (hereinafter referred to as“information for backhaul establishment”) for the base station 20.

—Contents of Information for Backhaul Establishment

In one example, the information for backhaul establishment includesidentification information of a base station to be connected (i.e.,identification information of the first base station 100), informationindicating a frequency band for the wireless backhaul, informationindicating the maximum transmission power for the wireless backhaul,and/or information indicating a duplex scheme to be applied. This makesit possible, for example, for the second base station 20 to performsettings for establishing the wireless backhaul.

Furthermore, the information for backhaul establishment may includetrigger information used to trigger switching between operation modes ofthe second base station 20. The switching may be the switching from afirst operation mode to a second operation mode. In one example, thefirst operation mode is the operation mode for operating as a mobilestation, and the second operation mode is the operation mode foroperating as a base station. In another example, the first operationmode may be the operation mode for performing wireless communicationwith the terminal device 30, and the second operation mode may be thesecond operation mode for stopping wireless communication with theterminal device 30 (e.g., off mode, sleep mode, and standby mode). Inaddition, the trigger information may include identification informationof the second base station 20 to be switched between operation modes.The identification information may be a cell ID of a base station in thecase of operating as a base station, and may be information foridentifying a mobile station (e.g., UE identify index, SAE temporarymobile subscriber identity (S-TMSI), and international mobile subscriberidentity (MI)).

—Providing Technique

In one example, the first base station 100 (the controller 157)broadcasts the information for backhaul establishment. Specifically, inone example, the first base station 100 (the controller 157) broadcastssystem information including the information for backhaul establishment.In this regard, the second base station 20 operating as a mobilestation, when it is determined that the second base station 20 is atarget whose operation mode is to be switched based on theidentification information included in the broadcasted systeminformation, may perform switching between operation modes based on thetrigger information.

Alternatively, the first base station 100 (the controller 157) mayprovide the information for backhaul establishment using pagingtechnique for the one or more second base stations 20. Specifically, thefirst base station 100 (the controller 157) notifies the one or moresecond base stations 20 by paging, and then may provide the informationfor backhaul establishment for each of the one or more second basestations 20.

Moreover, one of broadcasting and paging may be selected depending onthe number of second base stations 20 included in the one or more secondbase stations 20. In one example, if the number is one, then paging maybe selected, but if the number is two or more, the broadcasting may beselected.

(b-2) Operation in Response to Connection Request

In one example, the backhaul establishment procedure includes anoperation to be performed in response to a connection request from thesecond base station 20.

Specifically, in one example, the first base station 100 (the controller157) performs processing necessary for the wireless backhaul, such assecuring a wireless resource (e.g., securing a frequency band and aperiod) and/or scheduling a wireless resource, in response to aconnection request from the second base station 20. Furthermore, in oneexample, the first base station 100 (the controller 157) responds to theconnection request. In one example, the second base station 20 isnotified that the wireless backhaul is established as the response. Inthis regard, the securing and/or scheduling of a wireless resource maybe controlled dynamically based on the traffic volume processed by thesecond base station 20. In one example, for the second base station 20that handles a relatively high traffic volume, wireless resources morethan those of other second base stations 20 are secured. Moreover, theinformation relating to traffic may be notified from the second basestation 20 to the first base station 100 through the control plane. Inaddition, notification of the information relating to traffic to thebase station 100 may be triggered with a change in traffic. In otherwords, when the traffic to be processed is increased or decreasedsignificantly, the notification described above may be performed.Furthermore, the securing and scheduling of wireless resources may becontrolled dynamically based on the quality of communication between thefirst base station 100 and the second base station 20. The communicationquality may be reference signal received power (RSRP), reference signalreceived quality (RSRQ), or channel quality indicator (CQI) included inthe measurement result reported by the second base station 20. In thisregard, the wireless resource may be secured in units of resourceblocks.

In one example, the establishment of wireless backhaul between the firstbase station 100 and each of the one or more second base stations 20 iscontrolled as described above. This makes it possible, for example, toarrange cells according to dynamically changing traffic conditions.

(3) Plurality of Second Base Stations

In one example, the first base station 100 (the selector 151) selects aplurality of second base stations 20 located within the coverage 10 ofthe first base station 100. Furthermore, the first base station 100 (theinformation acquisition unit 155) acquires the information indicatingthe plurality of second base stations 20. The first base station 100(the controller 157) controls the establishment of the wireless backhaulbetween the first base station 100 and each of the one or more secondbase stations 20.

(4) Grouping of Second Base Stations 20

In one example, the first base station 100 (the grouping unit 153)performs grouping of the plurality of second base stations 20. In thisgrouping, the second base stations 20 that can have mutually independentpaths in wireless communication with the first base station 100(hereinafter referred to as “independent path”) are placed in the samegroup.

Moreover, in one example, the first base station 100 simultaneouslyperforms wireless communication with the second base stations 20included in the same group using the same frequency band (e.g., the samecomponent carrier), which will be described later.

(a) Independent Path

In one example, the independent path is a path having low correlationwith each other, a path that does not interfere with each other, or apath where interference is equal to or less than a threshold value.Moreover, the independent path may be a path obtained by performing theprecoding process based on channel information.

(b) Example of Grouping

FIG. 4 is a diagram illustrated to describe an example of grouping ofthe plurality of second base stations 20. Referring to FIG. 4, the firstbase station 100 and six second base stations 20 (i.e., second basestations 20A to 20F) located within the coverage 10 of the first basestation 100 are illustrated. In this example, five second base stations20 (i.e., the second base stations 20A, 20B, 20D, 20E, and 20F) areselected from among the six second base stations 20. Then, the fivesecond base stations 20 are grouped. The second base stations 20A, 20D,and 20F can have mutually independent paths in wireless communicationwith the first base station 100, and grouping of them allows a firstgroup to which the second base stations 20A, 20D, and 20F belong to beobtained. Furthermore, the second base stations 20B and 20E can alsohave mutually independent paths in wireless communication with the firstbase station 100, and grouping of them allows a second group to whichthe second base stations 20B and 20E belong to be obtained.

(c) Limitation on the Number of Second Base Stations 20

In one example, the first base station 100 (the grouping unit 153)performs the grouping such that the number of second base stations 20included in each group is equal to or less than the number of antennaelements or transceivers provided in the first base station 100.

(d) Downlink/Uplink

In one example, the first base station 100 (the grouping unit 153)performs the process of grouping the plurality of second base stations20 for each of downlink and uplink. In other words, the grouping unit153 performs the grouping for the downlink, and thereby obtaining one ormore groups for the downlink. Furthermore, the grouping unit 153performs the grouping for the uplink, and thereby obtaining one or moregroups for the uplink.

This makes it possible, for example, to perform wireless communicationsuitable for each of downlink and uplink.

Moreover, the downlink in this example is the link directed from thefirst base station 100 to the second base station 20, and the uplink inthis example is the link directed from the second base station 20 to thefirst base station 100.

(d-1) Downlink

In one example, the use of multi-user multiple-input multiple-output(MIMO) allows the plurality of second base stations 20 to haveindependent paths. In one example, independent paths can be formed byspatial multiplexing or beamforming. In spatial multiplexing, theprecoding process is performed. In beamforming, a multiplication of aset of antenna weights is performed.

Thus, in one example, the grouping for the downlink allows the secondbase station 20 that is a target of transmission by the multi-user MIMO(i.e., the second base station 20 capable of having the independentpath) to be placed in the same group.

Moreover, in the grouping for the downlink, the second base stations 20that are difficult to interfere with each other in wirelesscommunication with the first base station 100 may be placed in the samegroup.

(d-2) Uplink

In one example, in the grouping for the uplink, the second base stations20 that are difficult to interfere with each other in the wirelesscommunication with the first base station 100 are placed in the samegroup.

Moreover, the grouping for the uplink allows the second base station 20that is a target of reception by the multi-user MIMO (i.e., the secondbase station 20 capable of having the independent path) to be placed inthe same group.

(d-3) Example of Grouping

The one or more groups for the uplink may differ from the one or moregroups for the downlink.

Referring again to FIG. 4, in one example, the grouping for the uplinkallows a group to which the second base stations 20A, 20D, and 20Fbelong to be obtained. On the other hand, the grouping for the downlinkallows a group to which the second base stations 20A and 20F belong anda group to which only the second base station 20D belongs to beobtained. Thus, in one example, transmission to the second base station20D is performed on the downlink by single-user MIMO. This isparticularly effective in the case where the traffic volume of thesecond base station 20D is large.

As described above, in one example, the grouping is performed for eachof the downlink and the uplink, but the first embodiment is not limitedto this example. The grouping may be performed only for the downlink, orthe grouping may be performed for only the uplink.

(e) Grouping Based on Information Relating to Position of Second BaseStation 20

In one example, the first base station 100 (the grouping unit 153)performs the grouping of the plurality of second base stations 20 basedon the information relating to a position of each of the plurality ofsecond base stations 20.

(e-1) Information Relating to Position

In one example, the information relating to a position is informationindicating a position of each of the plurality of second base stations20. The position may be a position relative to the first base station100 or may be an absolute position.

In another example, the information relating to a position may beinformation indicating the direction directed from the first basestation 100 to the second base station 20. The direction may becalculated by estimating the direction of arrival of a signaltransmitted by the second base station 20.

(e-2) Example of Grouping

In one example, the grouping unit 153 places the second base stations 20located in different directions by more than a predetermined degree inthe same group. An example of the grouping is now described withreference to FIG. 5.

FIG. 5 is a diagram illustrated to describe an example of the groupingbased on the information relating to a position. Referring to FIG. 5,the first base station 100 and the six second base stations 20 (i.e.,the second base stations 20A to 20F) are illustrated, which is similarto FIG. 4. In one example, provided that the position of the first basestation 100 is represented by 0 and the positions of the second basestations 20A, 20D, and 20F are represented by A, B, and C, respectively,the angles formed by AOB, BOC, and COA are all equal to or larger than athreshold value (e.g., 90 degrees). Thus, the grouping allows the secondbase stations 20A, 20D, and 20F to be placed in the same group.

The predetermined degree (e.g., the threshold value) may be determineddepending on the directivity of an antenna of the first base station 100and/or the directivity of an antenna of the second base station 20. Inthis regard, the directivity may be the directivity of the antennaalone, the directivity of an array of the antennas, or the directivityobtained by beamforming. Moreover, the antenna may be an antenna of aremote radio head (RRH). In addition, in the case where the antenna ofthe first base station 100 is arranged for each sector, the anglebetween the sectors may be taken into consideration to determine thethreshold value.

As described above, the grouping may be performed based on theinformation relating to the position of the second base station 20. Thismakes it possible, for example, for the second base station 20 capableof having an independent path to be placed in the same group.

(f) Grouping Based on Information Relating to Traffic of Second BaseStation 20

In one example, the first base station 100 (the grouping unit 153)performs the grouping of the plurality of second base stations 20 basedon information relating to traffic of each of the plurality of secondbase stations 20. In one example, the information relating to traffic isinformation indicating a traffic volume.

Specifically, in one example, in the case where the traffic of onesecond base station 20 out of two or more second base stations 20included in one group is larger than the traffic of another second basestation 20, the one second base station 20 is placed in another group(e.g., a new group). A specific example is now described with referenceto FIG. 6.

FIG. 6 is a diagram illustrated to describe an example of the groupingbased on the information relating to traffic. Referring to FIG. 6, thefirst base station 100 and the six second base stations 20 (i.e., thesecond base stations 20A to 20F) are illustrated, which is similar toFIG. 4. In this example, the second base stations 20A, 20D, and 20Fbelong to the first group, which is similar to FIG. 4, but with theincrease in the traffic volume of the second base station 20D, thesecond base station 20D is excluded from the first group and placed in athird group (a new group).

This makes it possible, for example, to adjust the data rate in thewireless backhaul for the second base station 20 with the increase ordecrease in the traffic volume of the second base station 20. In oneexample, for the second base station 20D belonging to the third group,the transmission at a high data rate by spatial multiplexing orbeamforming can be performed by single-user MIMO.

(g) Grouping Based on Result of Measurement by Second Base Station 20

The first base station 100 (the grouping unit 153) may perform thegrouping of the plurality of second base stations 20 based on a resultobtained by measuring the reference signal by each of the plurality ofsecond base stations 20.

(g-1) Measurement

The measurement may be a measurement of the reception power of thereference signal, and the measurement result may be the reception power.Specifically, the measurement may be a measurement of the referencesignal received signal (RSRP), and the measurement result may be theRSRP. The second base station 20 may perform the measurement and mayreport the measurement result to the first base station 100. The firstbase station 100 may instruct the second base station 20 to report themeasurement.

The first base station 100 may transmit different reference signals toeach antenna port (or each group of antennas), and the measurement maybe a measurement for each antenna port (or each group of antennas). Anexample of the reference signal is now described with reference to FIG.7.

FIG. 7 is a diagram illustrated to describe an example of a referencesignal in the case of two layers. Referring to FIG. 7, resource blocksof an antenna port 0 and an antenna port 1 are illustrated. The resourceblock has 12 subcarriers in the frequency direction and has one slot inthe time direction. The first base station 100 transmits a cell-specificreference signal (CRS) through the antenna port 0 using some resourceelements of each resource block, and transmit the CRS through theantenna port 1 using some other resource elements of each resourceblock. The second base station 20 performs a measurement for each of theantenna ports 0 and 1.

Moreover, the example in which the reference signal is the CRS has beendescribed, but the reference signal is not limited to this example. Inone example, the reference signal may be a UE-specific reference signalknown as a demodulation reference signal (DM-RS).

(g-2) Example of Grouping

First Example

In a first example, the following RSRPs are obtained as a measurementresult of each of the second base stations 20A and 20B.

TABLE 1 Second Base Station 20A Second Base Station 20B RSRP (Port 0)−60 dBm −58 dBm RSRP (Port 1) −95 dBm −97 dBm

In this example, the second base stations 20A and 20B measure thesimilar RSRPs at the antenna ports 0 and 1, and thus it is determinedthat they fail to have an independent path. Thus, the second basestations 20A and 20B are not placed in the same group.

Second Example

In a second example, the following RSRPs are obtained as a measurementresult of each of the second base stations 20 A and 20B.

TABLE 2 Second Base Station 20A Second Base Station 20B RSRP (Port 0)−60 dBm −95 dBm RSRP (Port 1) −97 dBm −62 dBm

In this example, the second base stations 20A and 20B measuresignificantly different RSRPs at the antenna ports 0 and 1, and thus itis determined that they can have an independent path. Thus, the secondbase stations 20A and 20B are placed in the same group.

As described above, the grouping may be performed based on the result ofthe measurement performed by the second base station 20. This makes itpossible, for example, to place the second base station 20 capable ofhaving an independent path in the same group. In other words, this isequivalent to the fact that the first base station 100 estimates thedirection of arrival of the second base station 20 (e.g., the secondbase stations 20A and 20B).

(h) Grouping Based on Information Relating to Antenna of Second BaseStation 20

The first base station 100 (the grouping unit 153) may perform thegrouping of the plurality of second base stations 20 based oninformation relating to the antenna of each of the plurality of secondbase stations 20.

The information relating to the antenna may indicate the number ofantennas included in the second base station 20, the directivity of theantenna, the correlation coefficient between the antennas, and the like.

The first base station 100 (the grouping unit 153) may calculate thenumber of data streams that can be transmitted or receivedsimultaneously based on the information relating to the antenna and mayperform the grouping based on the calculated number.

In one example, the plurality of second base stations 20 are grouped asdescribed above. This makes it possible, for example, to increase thedata rate in the wireless backhaul.

(5) Allocation to Group

In one example, the first base station 100 (the controller 157) performallocation to each of two or more groups.

(a) Allocation of Period

In one example, the first base station 100 (the information acquisitionunit 155) acquires information indicating two or more groups obtained bygrouping the plurality of second base stations 20. Then, the first basestation 100 (the controller 157) allocates different periods forwireless communication with the first base station 100 to each of thetwo or more groups.

(a-1) Period

In one example, the different periods are one or more differentsubframes. In other words, one or more different subframes for wirelesscommunication with the first base station 100 are allocated to each ofthe two or more groups. A specific example is now described withreference to FIGS. 8 and 9.

FIG. 8 is a diagram illustrated to describe a first example of asubframe allocated to each group. Referring to FIG. 8, 10 subframes(i.e., one wireless frame) are illustrated. In one example, as in theexample of FIG. 4, a first group and a second group are obtained bygrouping a plurality of second base stations 20. In this example,consecutive subframes with subframe numbers 0 to 5 are allocated to thefirst group, and consecutive subframes with subframe numbers 6 to 9 areallocated to the second group.

FIG. 9 is a diagram illustrated to describe a second example of asubframe allocated to each group. Referring to FIG. 9, 10 subframes(i.e., one wireless frame) are illustrated. In one example, as in theexample of FIG. 4, a first group and a second group are obtained bygrouping a plurality of second base stations 20. In this example,subframes with subframe numbers 0, 3, 5, 7, and 8 are allocated to thefirst group, and subframes with subframe numbers 1, 2, 4, 6, and 9 areallocated to the second group.

Alternatively, the different periods may be one or more differentwireless frames or may be one or more different slots, instead of theone or more different subframes.

(a-2) Operation of Second Base Station 20 in Allocated Period

In one example, the first base station 100, in a period allocated to agroup, performs wireless communication with two or more second basestations 20 belonging to the group using the same frequency band. In oneexample, the first base station 100 simultaneously performs wirelesscommunication with two or more second base stations 20 belonging to thegroup using the same frequency band by multi-user MIMO.

Referring again to FIGS. 4 and 8, in one example, the first base station100 simultaneously performs wireless communication with the second basestations 20A, 20D, and 20F belonging to the first group using the samefrequency band by multi-user MIMO in the subframes (subframes withsubframe numbers 0 to 5) allocated to the first group. The first basestation 100 simultaneously performs wireless communication with thesecond base stations 20B and 20E belonging to the second group using thesame frequency by multi-user MIMO in the subframes (subframes withsubframe numbers 6 to 9) allocated to the second group.

(b) Allocation of Frequency Band

The first base station 100 (the controller 157) may allocate differentfrequency bands for wireless communication with the first base station100 to each of the two or more groups. The frequency band may be acomponent carrier.

Referring again to FIG. 4, in one example, the first group and thesecond group are obtained by grouping the plurality of second basestations 20. In this case, a first component carrier may be allocated tothe first group, and a second component carrier may be allocated to thesecond group.

The first base station 100 may use the frequency band allocated to agroup to perform simultaneously wireless communication with two or moresecond base stations 20 belonging to the group. In one example, thefirst base station 100 may perform simultaneously wireless communicationwith two or more second base stations 20 belonging to the group usingthe frequency band by multi-user MIMO.

(c) Others —Downlink/Uplink

The first base station 100 (the controller 157) may allocate differentperiods (or different frequency bands) for wireless communication withthe first base station 100 to each of the two or more groups for each ofdownlink and uplink.

—Allocation Depending on Change in Traffic

Furthermore, the first base station 100 (the controller 157) also maydynamically change the allocation of the period (or the frequency band)(e.g., depending on the change in traffic).

The allocation to the group performed as described above makes itpossible, for example, to increase the data rate in the wirelessbackhaul.

(6) Allocation of Antenna Element

In one example, the first base station 100 (the information acquisitionunit 155) acquires information indicating a group obtained by groupingthe plurality of second base stations 20. Then, the first base station100 (the controller 157) allocates one or more antenna elements among aplurality of antenna elements of the first base station 100 to each ofthe second base stations 20 belonging to the group.

Furthermore, in one example, the first base station 100 (the controller157) allocates one or more antenna elements out of the plurality ofantenna elements to each of the transceivers included in the first basestation 100. In one example, each transmitter corresponds to any one ofthe second base stations 20.

(a) Allocation Technique

(a-1) First Example: Direction of Arrival of Signal Transmitted bySecond Base Station 20

In a first example, the first base station 100 (the controller 157)allocates the one or more antenna elements to each of the second basestations 20 belonging to the group based on information relating to thedirection of arrival of a signal transmitted by each of the second basestations 20 belonging to the group.

In one example, the information relating to the direction of arrival isinformation indicating the direction of arrival. In this case, in oneexample, the first base station 100 estimates the direction of arrival.Alternatively, the information relating to the direction of arrival maybe information indicating the position of the second base station 20,and the first base station 100 may estimate the direction of arrivalbased on the position.

In one example, the first base station 100 (the controller 157)allocates one or more antenna elements suitable for the direction ofarrival of the signal transmitted by the second base station 20 fromamong the plurality of antenna elements to the second base stations 20.In one example, the one or more antenna elements suitable for thedirection of arrival are one or more antenna elements suitable fortransmitting or receiving a signal to or from the direction of arrival.

(a-2) Second Example: Quality of Propagation Channel

In a second example, the first base station 100 (the controller 157) mayallocate the one or more antenna elements to each of the second basestations 20 belonging to the group. This allocation is performed basedon information relating to the quality of a propagation channel betweeneach of the second base stations 20 belonging to the group and the firstbase station 100.

The information relating to the quality of the propagation channel maybe the result of measurement performed by the second base station 20.The measurement may be a measurement of reception power and/or receptionquality of the reference signal transmitted by the first base station100. The reference signal may be the CRS or may be other referencesignals (e.g., DM-RS). More specifically, the measurement may be ameasurement of the RSRP and/or reference signal received quality (RSRQ).The first base station 100 may acquire the measurement result through ameasurement report by the second base station 20. The first base station100 may instruct the second base station 20 to report the measurement.

The measurement may be a measurement of the reference signal transmittedfor each antenna element, and an antenna element with a moresatisfactory measurement result may be allocated to the second basestation 20. In this case, the first base station 100 may transmit thereference signal for each antenna element.

(b) Example of Allocation

(b-1) First Example

FIG. 10 is a diagram illustrated to describe a first example ofallocation of antenna elements to each of the second base stations 20.Referring to FIG. 10, there are illustrated an antenna element 111, atransceiver 161, a switch 163, a phase controller 165, and an amplitudecontroller 167, which are included in the first base station 100. Inthis example, the antenna elements 111B, 111E, and 111G are allocated tothe second base stations 20A, 20D, and 20F, respectively. The switch 163connects the transceivers 161B, 161E, and 161G to the antenna elements111B, 111E, and 111G, respectively. The transceivers 161B, 161E, and161G perform processing for transmission and reception to and from thesecond base stations 20A, 20D, and 20F, respectively. The first basestation 100 wirelessly communicates with the second base stations 20A,20D, and 20F belonging to the same group by multi-user MIMO, using theantenna elements 111B, 111E, and 111G, respectively.

In the example of FIG. 10, the number of the antenna elements 111, thenumber of the transceivers 161, the number of the phase controllers 165,and the number of the amplitude controllers 167 are respectively eight,but it should be appreciated that these numbers are not limited toeight. In addition, in the example of FIG. 10, these numbers are thesame number (i.e., 8), but it should be appreciated that these numbersmay be different. In these regards, the examples of FIGS. 11 and 12 arealso similar to the example of FIG. 10.

Furthermore, the control by the phase controller 165 and the amplitudecontroller 167 may be implemented by complex signal processing. In theseregards, the examples of FIGS. 11 to 13 are also similar to the exampleof FIG. 10.

(b-2) Second Example

FIG. 11 is a diagram illustrated to describe a second example ofallocation of antenna elements to each of the second base stations 20.In this example, the antenna elements 111A, 111B, and 111C are allocatedto the second base station 20A, the antenna elements 111D, 111E, and111F are allocated to the second base station 20D, and the antennaelements 111G and 111H are allocated to the second base station 20F. Theswitch 163 connects the transceiver 161B to the antenna elements 111A,111B, and 111C, connects the transceiver 161E to the antenna elements111D, 111E, and 111F, and connects the transceiver 161G to the antennaelements 111G and 111H. The transceiver 161B performs processing fortransmission and reception to and from the second base station 20A. Thetransceiver 161E performs processing for transmission and reception toand from the second base station 20D. The transceiver 161G performsprocessing for transmission and reception to and from the second basestation 20F. In one example, the first base station 100 transmits asignal to the second base station 20A by beamforming using the antennaelements 111A, 111B, and 111C. In one example, the first base station100 controls the phase of a signal in each of the phase controllers165A, 165B, and 165C for beamforming and controls the amplitude of asignal in each of the amplitude controllers 167A, 167B, and 167C.Specifically, in one example, the first base station 100 controls thephase and amplitude so that the maximum directivity of the formed beamis closer to the direction of arrival of a signal from the second basestation 20A. Alternatively, the first base station 100 (e.g., thecontroller 157) may control the phase and amplitude so that the nulldirection of the formed beam is closer to the direction of arrival of asignal from the second base station 20 D and/or the second base station20F. Similarly, in one example, the first base station 100 transmits asignal to the second base station 20D by beamforming using the antennaelements 111D, 111E, and 111F, and transmits a signal to the second basestation 20F by beamforming using the antenna elements 111G and 111H.

Moreover, the first base station 100 may transmit a signal to the secondbase station 20 by diversity instead of beamforming. In one example, thetransmission by diversity may be performed in an environment wheresignal to noise ratio (SNR) is low or where degradation due to fadingbecomes significantly more severe. In one example, selection of a paththat provides the highest SNR, phase matching and multiplication of thesame weight, or maximization of SNR by multiplication of the weight ofeach path signal may be performed.

(b-3) Third Example

FIG. 12 is a diagram illustrated to describe a third example ofallocation of antenna elements to each of the second base stations 20.In this example, similarly to the example of FIG. 11, the antennaelements 111A, 111B, and 111C are allocated to the second base station20A, the antenna elements 111D, 111E, and 111F are allocated to thesecond base station 20D, and the antenna elements 111G and 111H areallocated to the second base station 20F. Furthermore, similarly to theexample of FIG. 11, the switch 163 connects the transceiver 161B to theantenna elements 111A, 111B, and 111C, and connects the transceiver 161Gto the antenna elements 111G and 111H. The transceiver 161B performsprocessing for transmission and reception to and from the second basestation 20A. The transceiver 161G performs processing for transmissionand reception to and from the second base station 20F. In particular, inthis example, it is determined that an independent path can be formedamong the antenna elements 111D, 111E, and 111F. Thus, the switch 163connects the transceiver 161D to the antenna element 111D, connects thetransceiver 161E to the antenna element 111E, and connects thetransceiver 161F to the antenna element 111F. Each of the transceivers161D, 161E, and 161F performs processing for transmission and receptionto and from the second base station 20D. Then, the first base station100 performs wireless communication with the second base station 20D bysingle-user MIMO.

(c) Case of No Allocation of Antenna Element

One or more of the plurality of antenna elements included in the firstbase station 100 may be prevented from being allocated to each of thesecond base stations 20 belonging to the same group. Alternatively, theplurality of antenna elements may be shared between the second basestations 20 belonging to the same group.

FIG. 13 is a diagram illustrated to describe an example of a case wherethere is no allocation of antenna elements to the second base station20. Referring to FIG. 13, there are illustrated the antenna element 111,the transceiver 161, the phase controller 165, and the amplitudecontroller 167, which are included in the first base station 100. Thetransceiver 161A performs processing for transmission and reception toand from the second base station 20A. Similarly, the signal generated bythe transceiver 161A is transmitted from the antenna element 111A viathe phase controller 165A and the amplitude controller 167A. Similarly,the signal is transmitted from the antenna element 111B via the phasecontroller 165D and the amplitude controller 167D, and the signal istransmitted from the antenna element 111C via the phase controller 165Gand the amplitude controller 167G. Thus, in one example, a beam 91A isformed in the direction of arrival of the signal transmitted by thesecond base station 20A. Similarly, the signal generated by thetransceiver 161B is transmitted from each of the antenna elements 111B,111E, and 111H, and consequently, in one example, a beam 91B is formedin the direction of arrival of the signal transmitted by the second basestation 20B. Furthermore, the signal generated by the transceiver 161Cis transmitted from each of the antenna elements 111C, 111F, and 111I,and consequently, in one example, a beam 91C is formed in the directionof arrival of the signal transmitted by the second base station 20C.

(7) Selection of Multi-Antenna Communication Scheme

In one example, the first base station 100 (the information acquisitionunit 155) acquires information indicating a group obtained by groupingthe plurality of second base stations 20. Then, the first base station100 (the controller 157) selects a multi-antenna communication scheme tobe applied to the group. Thus, the first base station 100 performswireless communication with the second base station 20 included in thegroup according to the selected communication scheme.

(a) Multi-Antenna Communication Scheme

In one example, the communication scheme is diversity, spatialmultiplexing, or beamforming.

In one example, the communication scheme is single-user MIMO ormulti-user MIMO.

(b) Selection Technique

(b-1) Number of Second Base Stations 20 Included in Group

In a first example, the first base station 100 (the controller 157)selects the communication scheme based on the number of second basestations 20 belonging to the group.

More specifically, in one example, in the case where the group includesonly one second base station 20, the first base station 100 (thecontroller 157) selects the single-user MIMO as the communication schemeto be applied to the group. On the other hand, in the case where thegroup includes two or more second base stations 20, the first basestation 100 (the controller 157) selects the multi-user MIMO as thecommunication scheme to be applied to the group.

(b-2) Quality of Propagation Channel Between First Base Station 100 andSecond Base Station 20

In a second example, the first base station 100 (the controller 157) mayselect the communication scheme based on information relating to thequality of a propagation channel between each of the second basestations 20 belonging to the group and the first base station 100.

The information relating to the quality of the propagation channel maybe the result of measurement by the second base station 20. Themeasurement may be a measurement of the reception power and/or receptionquality of the reference signal transmitted by the first base station100. The reference signal may be the CRS or other reference signals(e.g., DM-RS). More specifically, the measurement may be a measurementof RSRP and/or RSRQ. The first base station 100 may acquire the resultof the measurement through a report of the measurement by the secondbase station 20. The first base station 100 may instruct the second basestation 20 to report the measurement.

Specifically, in one example, if the quality of the propagation channelis not satisfactory, the first base station 100 (the controller 157) mayselect the diversity as the communication scheme to be applied to thegroup. Otherwise, the first base station 100 (the controller 157) mayselect the beamforming or spatial multiplexing as the communicationscheme to be applied to the group.

In one example, the multi-antenna communication scheme is selected asdescribed above. This makes it possible, for example, to implementsatisfactory wireless communication depending on the environment.

(8) Operation for Measurement

In one example, the first base station 100 (the controller 157) performsan operation for causing the terminal device 30 to measure the cell ofthe one or more second base stations 20.

In a first example, the first base station 100 (the controller 157)generates system information including a neighbor cell list having acell ID of the one or more second base stations 20. In one example, thesystem information is system information block (SIB) 4 and/or SIB 5.Then, the first base station 100 reports the system information.

In a second example, the first base station 100 (the controller 157)generates a measurement configuration (measurement configurationmessage) including a cell list having a cell ID of the one or moresecond base stations 20. Then, the first base station 100 transmits themeasurement configuration message to the terminal device 30.

This makes it possible, for example, to select a cell of the second basestation 20 in the cell selection/cell reselection by the terminal device30 or the handover of the terminal device 30.

<3.2. Processing Procedure>

An example of processing according to the first embodiment is nowdescribed with reference to FIG. 14. FIG. 14 is a sequence diagramillustrating an example of a schematic procedure of processing accordingto the first embodiment.

The first base station 100 selects one or more second base stations 20located within the coverage 10 of the first base station 100 (S401). Inone example, the first base station 100 selects the one or more secondbase stations 20 in the case where a predetermined condition on thetraffic of the first base station 100 is satisfied. In one example, thefirst base station 100, when selecting two or more second base stations20, performs grouping of the two or more second base stations 20.

Then, the first base station 100 provides information for establishing awireless backhaul between the first base station 100 and the second basestation 20 (i.e., information for backhaul establishment) for theselected one or more second base stations 20 (S403). In one example, theinformation for backhaul establishment includes identificationinformation of a base station to be connected (i.e., identificationinformation of the first base station 100), information indicating afrequency band for the wireless backhaul, information indicating themaximum transmission power for the wireless backhaul, and/or informationindicating a duplex scheme to be applied.

The second base station 20 configures settings for connection with thefirst base station 100 based on the information for backhaulestablishment (S405). An example of the settings includes a frequencyband, maximum transmission power, and/or duplex scheme.

Then, the second base station 20 requests a connection to the first basestation 100 (S407). In one example, the second base station 20 transmitsa connection request message to the first base station 100.

The first base station 100 performs processing necessary for thewireless backhaul in response to the connection request (S407). In oneexample, the processing includes securing a wireless resource (e.g.,securing a frequency band and a period) and/or scheduling a wirelessresource.

Furthermore, the first base station 100 responds to the connectionrequest (S411). In one example, the first base station 100 transmits aresponse message to the second base station 20. In one example, thesecond base station 20 is notified that the wireless backhaul isestablished in this response.

Then, the first base station 100 and the selected one or more secondbase stations 20 perform transmission and reception through the wirelessbackhaul (S413). In one example, the one or more second base stations 20communicate with a core network via the first base station 100.

4. Second Embodiment

Subsequently, a second embodiment of the present disclosure is nowdescribed with reference to FIG. 15.

As described above, various operations relating to the wireless backhaulare performed by the first base station 100 in the first embodiment. Onthe other hand, some or all of the various operations relating to thewireless backhaul are performed in the second embodiment by the controldevice 200 instead of the first base station 100.

<4.1. Technical Features>

Technical features according to the second embodiment are now described.

(1) Selection of Second Base Station 20

In one example, the control device 200 (the selector 231) selects one ormore second base stations 20 located within the coverage 10 of the firstbase station 100.

There is no difference in description on this point between the firstand second embodiments, except for the subject performing operations.Thus, redundant description will be omitted. Information necessary forselecting the second base station 20 may be provided for the controldevice 200 from the first base station 100 (or other nodes).

(2) Control of Establishment of Wireless Backhaul (a) Control Device 200

The control device 200 (the information acquisition unit 235) acquiresinformation indicating one or more second base stations 20 locatedwithin the coverage 10 of the first base station 100. The control device200 (the controller 237) controls the establishment of the wirelessbackhaul between the first base station 100 and each of the one or moresecond base stations 20.

(a-1) One or More Second Base Stations 20

In one example, the one or more second base stations 20 are one or moresecond base stations selected by the selector 231 as described above.The information acquisition unit 235 acquires the information indicatingone or more second base stations 20 selected by the selector 231.

(a-2) Example of Control

In one example, the control of the establishment of the wirelessbackhaul includes providing information for establishing the wirelessbackhaul (hereinafter referred to as “information for backhaulestablishment”) for the first base station 100.

—Contents of Information for Backhaul Establishment

In one example, the information for backhaul establishment includesinformation indicating the one or more second base stations 20.

Furthermore, the information for backhaul establishment may includeinformation indicating a frequency band for the wireless backhaul,information indicating the maximum transmission power for the wirelessbackhaul, and/or information indicating a duplex scheme to be applied.

Furthermore, the information for backhaul establishment may includetrigger information used to trigger a procedure for establishing abackhaul by the first base station 100 (i.e., a procedure forestablishing the wireless backhaul with each of the one or more secondbase stations 20).

—Providing Technique

The control device 200 (the controller 237) provides the information forbackhaul establishment for the first base station 100 through the wiredbackhaul 40.

(b) First Base Station 100

The first base station 100 (the information acquisition unit 155)acquires information indicating one or more second base stations 20located within the coverage 10 of the first base station 100. The firstbase station 100 (the controller 157) controls the establishment of awireless backhaul between the first base station 100 and each of the oneor more second base stations 20.

(b-1) One or More Second Base Stations 20

In one example, the one or more second base stations 20 are one or moresecond base stations selected by the control device 200 (the selector231) as described above. The information acquisition unit 155 acquiresinformation indicating one or more second base stations 20 selected bythe control device 200 (the selector 231).

(b-2) Example of Control

In one example, the control of the establishment of the wirelessbackhaul includes performing a procedure (i.e., a backhaul establishmentprocedure) for establishing the wireless backhaul with each of the oneor more second base stations 20.

There is no difference in description on this point between the firstembodiment and the second embodiment. Thus, redundant description willbe omitted.

(3) Plurality of Second Base Stations

In one example, the control device 200 (the selector 231) selects aplurality of second base stations 20 located within the coverage 10 ofthe first base station 100.

Furthermore, the control device 200 (the information acquisition unit235) acquires the information indicating the plurality of second basestations 20, and the control device 200 (the controller 237) controlsthe establishment of the wireless backhaul between the first basestation 100 and each of the second base stations 20.

Furthermore, the first base station 100 (the information acquisitionunit 155) acquires the information indicating the plurality of secondbase stations 20, and the first base station 100 (the controller 157)controls the establishment of the wireless backhaul between the firstbase station 100 and each of the plurality second base stations 20.

(4) Grouping of Second Base Stations 20

In one example, the control device 200 (the grouping unit 233) performsgrouping of the plurality of second base stations 20. In grouping, thesecond base stations 20 capable of having mutually independent paths(i.e., an independent path) in the wireless communication with the firstbase station 100 are placed in the same group.

There is no difference in description on this point between the firstand second embodiments, except for the subject performing operations.Thus, redundant description will be omitted. Information necessary forgrouping the second base stations 20 may be provided for the controldevice 200 by the first base station 100 (or other nodes). Theinformation for backhaul establishment provided for the first basestation 100 by the control device 200 may include information indicatingone or more groups obtained by the grouping.

Moreover, instead of the grouping by the control device 200, the firstbase station 100 may perform the grouping as in the first embodiment inthe second embodiment.

(5) Allocation to Group

In one example, the first base station 100 (the controller 157) performsthe allocation (e.g., allocation of a period or a frequency band) toeach of two or more groups.

There is no difference in description on this point between the firstembodiment and the second embodiment. Thus, redundant description willbe omitted.

Moreover, instead of the first base station 100, the control device 200(the controller 237) may perform the allocation in the secondembodiment. In this case, the control device 200 (the informationacquisition unit 235) may acquire the information indicating the two ormore groups. In addition, the information necessary for the allocationmay be provided for the control device 200 by the first base station 100(or other nodes). The information for backhaul establishment providedfor the first base station 100 by the control device 200 may includeinformation indicating a result obtained from the allocation.

(6) Allocation of Antenna Elements

In one example, the first base station 100 (information acquisition unit155) acquires information indicating a group obtained by grouping theplurality of second base stations 20. Then, the first base station 100(the controller 157) allocates one or more antenna elements among aplurality of antenna elements of the first base station 100 to each ofthe second base stations 20 belonging to the group.

There is no difference in description on this point between the firstembodiment and the second embodiment. Thus, redundant description willbe omitted.

Moreover, instead of allocation of the one or more antenna elements toeach of the second base stations 20 belonging to the group by the firstbase station 100, the control device 200 (the controller 237) mayallocate the one or more antenna elements to each of the second basestations 20 belonging to the group in the second embodiment. In thiscase, the control device 200 (the information acquisition unit 235) mayacquire the information indicating the two or more groups. In addition,the information necessary for the allocation may be provided for thecontrol device 200 by the first base station 100 (or other nodes). Theinformation for backhaul establishment provided for the first basestation 100 by the control device 200 may include information indicatingthe result obtained by allocating antenna elements.

(7) Selection of Multi-Antenna Communication Scheme

In one example, the first base station 100 (information acquisition unit155) acquires information indicating a group obtained by grouping theplurality of second base stations 20. Then, the first base station 100(the controller 157) selects a multi-antenna communication scheme to beapplied to the group. Thus, the first base station 100 performs wirelesscommunication with the second base station 20 included in the groupaccording to the selected communication scheme.

There is no difference in description on this point between the firstembodiment and the second embodiment. Thus, redundant description willbe omitted.

Instead of the selection of the communication scheme by the first basestation 100, the control device 200 (the controller 237) may select thecommunication scheme. In this case, the control device 200 (theinformation acquisition unit 235) may acquire information indicating agroup obtained by grouping the plurality of second base stations 20. Inaddition, information necessary for selecting the communication schememay be provided for the control device 200 by the first base station 100(or other nodes). The information for backhaul establishment providedfor the first base station 100 by the control device 200 may includeinformation indicating the communication scheme.

(8) Operation for Measurement

In one example, the first base station 100 (the controller 157) performsan operation for causing the terminal device 30 to measure the cell ofthe one or more second base stations 20.

There is no difference in description on this point between the firstembodiment and the second embodiment. Thus, redundant description willbe omitted.

<4.2. Processing Procedure>

An example of processing according to the second embodiment is nowdescribed with reference to FIG. 15. FIG. 15 is a sequence diagramillustrating an example of a schematic procedure of processing accordingto the second embodiment.

The control device 200 selects one or more second base stations 20located within the coverage 10 of the first base station 100 (S441). Inone example, the control device 200 selects the one or more second basestations 20 in the case where a predetermined condition on the trafficof the first base station 100 is satisfied. In other words, if thepredetermined condition is satisfied, the control device 200 selects thefirst base station 100 and selects the one or more second base stations20. In one example, the control device 200, when selecting two or moresecond base stations 20, groups the two or more second base stations 20.

Then, the control device 200 provides information (i.e., information forbackhaul establishment) for establishing a wireless backhaul between thefirst base station 100 and the second base station 20 for the first basestation 100 (S443). In one example, the information for backhaulestablishment includes information indicating the selected one or moresecond base stations 20. Furthermore, the information for backhaulestablishment may include information indicating a frequency band forthe wireless backhaul, information indicating the maximum transmissionpower for the wireless backhaul, and/or information indicating a duplexscheme to be applied.

Furthermore, the first base station 100 provides information (i.e.,information for establishing backhaul establishment) for establishing awireless backhaul between the first base station 100 and the second basestation 20 for the selected one or more second base stations 20 (S445).In one example, the information for backhaul establishment includesidentification information of a base station to be connected (i.e.,identification information of the first base station 100), informationindicating a frequency band for the wireless backhaul, informationindicating the maximum transmission power for the wireless backhaul,and/or information indicating a duplex scheme to be applied.

The second base station 20 configures settings for connection with thefirst base station 100 based on the information for backhaulestablishment (S447). In one example, the settings include settings suchas a frequency band, maximum transmission power, and/or duplex scheme.

Then, the second base station 20 requests a connection to the first basestation 100 (S449). In one example, the second base station 20 transmitsa connection request message to the first base station 100.

The first base station 100 performs processing necessary for thewireless backhaul in response to the connection request (S451). In oneexample, the processing includes securing a wireless resource (e.g.,securing a frequency band and a period) and/or scheduling a wirelessresource.

Furthermore, the first base station 100 responds to the connectionrequest (S453). In one example, the first base station 100 transmits aresponse message to the second base station 20. In one example, in thisresponse, the second base station 20 is notified that a wirelessbackhaul is established.

Thus, the first base station 100 and the selected one or more secondbase stations 20 perform transmission and reception through the wirelessbackhaul (S455). In one example, the one or more second base stations 20communicate with a core network via the first base station 100.

<<5. Application Examples>>

The technology according to the present disclosure is applicable tovarious products. In one example, the control device 200 may beimplemented as any type of server such as a tower server, a rack server,and a blade server. In addition, at least a part of constituent elementsof the control device 200 may be implemented in a module (e.g., anintegrated circuit module configured in one die, or a card or bladeinserted into a slot of a blade server) mounted in a server.

In one example, the first base station 100 may be implemented as anytype of evolved Node B (eNB). In one example, the first base station 100may be implemented as a macro eNB. Alternatively, the first base station100 may be implemented as another type of base station such as a NodeBand a base transceiver station (BTS). The first base station 100 mayinclude a main body (also referred to as a base station device) that isconfigured to control wireless communication and one or more remoteradio heads (RRHs) that is disposed in a different place from the mainbody. Additionally, various types of terminals, which will be describedlater, may also operate as the first base station 100 by temporarily orsemi-permanently executing functions of a base station. Furthermore, atleast a part of constituent elements of the first base station 100 maybe implemented in a base station device or in a module intended for abase station device.

<5.1. Application Example for Control Device>

FIG. 16 is a block diagram illustrating an exemplary schematicconfiguration of a server 700 to which the technology according to thepresent disclosure may be applied. The server 700 includes a processor701, a memory 702, a storage 703, a network interface 704, and a bus706.

The processor 701 may be a central processing unit (CPU) or a digitalsignal processor (DSP) in one example, and controls various types offunctions of the server 700. The memory 702 includes random-accessmemory (RAM) and read-only memory (ROM), and stores programs executed bythe processor 701 or other data. The storage 703 may include a storagemedium such as a semiconductor memory and a hard disk.

The network interface 704 is a wired communication interface forconnecting the server 700 to a wired communication network 705. Thewired communication network 705 may be a core network such as an evolvedpacket core (EPC), or may be a packet data network (PDN) such as theInternet.

The bus 706 connects the processor 701, the memory 702, the storage 703,and the network interface 704 to each other. The bus 706 may include twoor more buses (such as a high-speed bus and a low-speed bus) each ofwhich has different speed.

In the server 700 shown in FIG. 16, one or more constituent elements(the selector 231, the grouping unit 233, the information acquisitionunit 235, and/or the controller 237) included in the processing unit 230described with reference to FIG. 3 may be incorporated in the processor701. In an example, a program for causing the processor to function asthe one or more constituent elements (i.e., a program for causing theprocessor to execute operations of the one or more constituent elements)may be installed in the server 700, and the processor 701 may executethe program. In another example, the server 700 may have a module thatincludes the processor 701 and the memory 702 to incorporate the one ormore constituent elements in the module. In this case, the module maystore a program for causing the processor to function as the one or moreconstituent elements in the memory 702, and the processor 701 mayexecute the program. As described above, the server 700 or the modulemay be provided as a device that includes the one or more constituentelements. The program for causing the processor to function as the oneor more constituent elements may be provided. In addition, a readablerecording medium on which the program is recorded may be provided.

<5.2. Application Example for First Base Station> First ApplicationExample

FIG. 17 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. The eNB 800 includes one or more antennas 810and a base station device 820. Each of the antennas 810 and the basestation device 820 may be connected to each other via an RF cable.

Each of the antennas 810 includes a single or multiple antenna elements(e.g., multiple antenna elements included in a MIMO antenna), and isused for the base station device 820 to transmit and receive wirelesssignals. The eNB 800 may include the multiple antennas 810 asillustrated in FIG. 17. In one example, the multiple antennas 810 may beindividually compatible with a plurality frequency bands used by the eNB800. Although FIG. 17 illustrates the example in which the eNB 800includes the multiple antennas 810, the eNB 800 may include a singleantenna 810.

The base station device 820 is configured to include a controller 821, amemory 822, a network interface 823, and a wireless communicationinterface 825.

The controller 821 may be, for example, a CPU or a DSP, and causesvarious functions of an upper layer of the base station device 820 to beexecuted. In one example, the controller 821 generates a data packetfrom data in a signal processed by the wireless communication interface825, and transfers the generated packet via the network interface 823.The controller 821 may bundle data from multiple baseband processors togenerate the bundled packet, and transfer the generated bundled packet.The controller 821 may have logical functions of performing control suchas wireless resource control, radio bearer control, mobility management,admission control, and scheduling. The control may be performed incorporation with an eNB or a core network node in the vicinity. Thememory 822 includes RAM and ROM, and stores a program that is executedby the controller 821, and various types of control data (e.g., a listof terminals, transmission power data, and scheduling data).

The network interface 823 is a communication interface for connectingthe base station device 820 to a core network 824. The controller 821may communicate with a core network node or another eNB via the networkinterface 823. In this case, the eNB 800, and the core network node orthe other eNB may be connected to each other through a logical interface(e.g., an S1 interface and an X2 interface). The network interface 823may also be a wired communication interface or a wireless communicationinterface for wireless backhaul. In the case where the network interface823 is a wireless communication interface, the network interface 823 mayuse a higher frequency band for wireless communication than a frequencyband used by the wireless communication interface 825.

The wireless communication interface 825 supports any cellularcommunication scheme such as Long Term Evolution (LTE) and LTE-Advanced,and provides wireless connection for a terminal positioned in a cell ofthe eNB 800 via the antenna 810. The wireless communication interface825 may typically include, for example, a baseband (BB) processor 826and an RF circuit 827. In one example, The BB processor 826 may performencoding/decoding, modulating/demodulating, andmultiplexing/de-multiplexing, and performs various types of signalprocessing of layers (e.g., L1, medium access control (MAC), radio linkcontrol (RLC), and a packet data convergence protocol (PDCP)). Insteadof the controller 821, the BB processor 826 may have a part or all ofthe logical functions. The BB processor 826 may be a memory that storesa communication control program, or a module that includes a processorand the related circuit configured to execute the program. Updating theprogram may allow functions of the BB processor 826 to be changed. Themodule may be a card or blade that is inserted into a slot of the basestation device 820. Alternatively, the module may also be a chip that ismounted on the card or the blade. Meanwhile, the RF circuit 827 mayinclude, for example, a mixer, a filter, and an amplifier, and transmitsand receives a wireless signal via the antenna 810.

The wireless communication interface 825 may include the multiple BBprocessors 826 as illustrated in FIG. 17. In one example, the multipleBB processors 826 may be individually compatible with multiple frequencybands used by the eNB 800. The wireless communication interface 825 mayinclude the multiple RF circuits 827 as illustrated in FIG. 17. In oneexample, the multiple RF circuits 827 may be individually compatiblewith multiple antenna elements. Although FIG. 17 illustrates the examplein which the wireless communication interface 825 includes the multipleBB processors 826 and the multiple RF circuits 827, the wirelesscommunication interface 825 may also include a single BB processor 826or a single RF circuit 827.

One or more of the constituent elements included in the processing unit150 (the selector 151, the grouping unit 153, the informationacquisition unit 155, and/or the controller 157) described above withreference to FIG. 2 may be incorporated in the wireless communicationinterface 825 of the eNB 800 shown in FIG. 17. Alternatively, the atleast part of these constituent elements may be incorporated in thecontroller 821. In an example, the eNB 800 may have a module thatincludes a part (e.g., the BB processors 826) or all of the constituentelements of the wireless communication interface 825 and/or thecontroller 821, and the one or more constituent elements may beincorporated in the module. In this case, the module may store a programfor causing a processor to function as the one or more constituentelements (i.e., a program for causing a processor to execute operationsof the one or more constituent elements), and to execute the program. Inanother example, a program for causing a processor to function as theone or more constituent elements may be installed in the eNB 800, andthe wireless communication interface 825 (e.g., the BB processors 826)and/or the controller 821 may execute the program. As described above,the eNB 800, the base station device 820, or the module may be providedas a device that includes the one or more constituent elements. Aprogram for causing a processor to function as the one or moreconstituent elements may be provided. In addition, a readable recordingmedium on which the program is recorded may be provided.

Furthermore, the wireless communication unit 120 described above withreference to FIG. 2 may be incorporated in the wireless communicationinterface 825 (e.g., the RF circuit 827) in the eNB 800 shown in FIG.17. In addition, the antenna unit 110 may be incorporated in the antenna810. Furthermore, the network communication unit 130 may be incorporatedin the controller 821 and/or the network interface 823.

Furthermore, in the eNB 800 shown in FIG. 17, the transceiver 161, thephase controller 165, and the amplitude controller 167, which aredescribed above with reference to FIGS. 10 to 13, may be incorporated inthe wireless communication interface 825 (e.g., the BB processor 826).Furthermore, the antenna element 111 may be incorporated in the antenna810.

Second Application Example

FIG. 18 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which the technology according to the presentdisclosure may be applied. An eNB 830 includes one or more antennas 840,a base station device 850, and an RRH 860. Each antenna 840 and the RRH860 may be connected to each other via an RF cable. The base stationdevice 850 and the RRH 860 may be connected to each other via ahigh-speed line such as an optical fiber cable.

Each of the antennas 840 includes a single or multiple antenna elements(e.g., multiple antenna elements included in a MIMO antenna), and isused for the RRH 860 to transmit and receive a wireless signal. The eNB830 may include the multiple antennas 840 as illustrated in FIG. 18. Inone example, the multiple antennas 840 may be individually compatiblewith multiple frequency bands used by the eNB 830. Although FIG. 18illustrates the example in which the eNB 830 includes the multipleantennas 840, the eNB 830 may include a single antenna 840.

The base station device 850 includes a controller 851, a memory 852, anetwork interface 853, a wireless communication interface 855, and aconnection interface 857. The controller 851, the memory 852, and thenetwork interface 853 are similar to the controller 821, the memory 822,and the network interface 823 described with reference to FIG. 17,respectively.

The wireless communication interface 855 supports any cellularcommunication scheme such as LTE and LTE-Advanced, and provides awireless connection to a terminal positioned in a sector correspondingto the RRH 860 via the RRH 860 and the antenna 840. The wirelesscommunication interface 855 may typically include, for example, a BBprocessor 856. The BB processor 856 is similar to the BB processors 826described above with reference to FIG. 17, except that the BB processors856 are connected to RF circuits 864 of the RRH 860 via the connectioninterface 857. The wireless communication interface 855 may include themultiple BB processors 856 as shown in FIG. 18. In one example, themultiple BB processors 856 may be individually compatible with multiplefrequency bands used by the eNB 830. Although FIG. 18 illustrates theexample in which the wireless communication interface 855 includes themultiple BB processors 856, the wireless communication interface 855 mayinclude a single BB processor 856.

The connection interface 857 is an interface for connecting the basestation device 850 (the wireless communication interface 855) to the RRH860. The connection interface 857 may also be a communication moduleintended for communication over the high-speed line that connects thebase station device 850 (the wireless communication interface 855) tothe RRH 860.

The RRH 860 includes a connection interface 861 and a wirelesscommunication interface 863.

The connection interface 861 is an interface for connecting the RRH 860(the wireless communication interface 863) to the base station device850. The connection interface 861 may also be a communication moduleintended for communication over the high-speed line.

The wireless communication interface 863 transmits and receives awireless signal via the antenna 840. The wireless communicationinterface 863 may typically include, for example, the RF circuit 864.The RF circuit 864 may include, for example, a mixer, a filter, and anamplifier, and transmits and receives a wireless signal via the antenna840. The wireless communication interface 863 may include multiple RFcircuits 864 as shown in FIG. 18. In one example, the multiple RFcircuits 864 may support multiple antenna elements individually.Although FIG. 18 illustrates the example in which the wirelesscommunication interface 863 includes the multiple RF circuits 864, thewireless communication interface 863 may include a single RF circuit864.

One or more constituent elements included in the processing unit 150(the selector 151, the grouping unit 153, the information acquisitionunit 155, and/or the controller 157) described above with reference toFIG. 2 may be incorporated in the wireless communication interface 855and/or the wireless communication interface 863 of the eNB 830 shown inFIG. 18. Alternatively, the at least part of these constituent elementsmay be incorporated in the controller 851. In an example, the eNB 830may have a module that includes a part or all of the constituentelements of the wireless communication interface 855 (e.g., the BBprocessors 856), and/or the controller 851, and one or more of theconstituent elements may be incorporated in the module. In this case,the module may store a program for causing a processor to function asthe one or more constituent elements (i.e., a program for causing aprocessor to execute operations of the one or more constituent elements)and to execute the program. In another example, a program for causing aprocessor to function as the one or more constituent elements may beinstalled in the eNB 830, and the wireless communication interface 855(e.g., the BB processors 856) and/or the controller 851 may execute theprogram. As described above, the eNB 830, the base station device 850,or the module may be provided as a device that includes the one or moreconstituent elements. A program for causing a processor to function asthe one or more constituent elements may be provided. In addition, areadable recording medium on which the program is recorded may beprovided.

Furthermore, the wireless communication unit 120 described above withreference to FIG. 2 may be incorporated in the wireless communicationinterface 863 (e.g., the RF circuit 864) of the eNB 830 shown in FIG.18. In addition, the antenna unit 110 may be incorporated in the antenna840. Furthermore, the network communication unit 130 may be incorporatedin the controller 851 and/or the network interface 853.

Furthermore, in the eNB 830 shown in FIG. 18, the transceiver 161, thephase controller 165, and the amplitude controller 167, which aredescribed above with reference to FIGS. 10 to 13, are incorporated inthe wireless communication interface 855 (e.g., the BB processor 856).Furthermore, the antenna element 111 may be incorporated in the antenna840.

6. Brief Summary

Each device and processing according to the embodiments of the presentdisclosure have been described with reference to FIGS. 1 to 18.According to the embodiments of the present disclosure, the first basestation 100 and/or the control device 200 is configured to include theinformation acquisition unit and the controller. The informationacquisition unit acquires information indicating the one or more secondbase stations 20 located within the coverage 10 of the first basestation 100 connected to the wired backhaul. The controller controls theestablishment of the wireless backhaul between the first base station100 and each of the one or more second base stations 20. This makes itpossible, for example, to perform cell arrangement flexibly with asmaller burden.

The preferred embodiment(s) of the present disclosure has/have beendescribed above with reference to the accompanying drawings, whilst thepresent disclosure is not limited to the above examples. A personskilled in the art may find various alterations and modifications withinthe scope of the appended claims, and it should be understood that theywill naturally come under the technical scope of the present disclosure.

In one example, the processing steps in each process in thisspecification are not strictly limited to execution in a time seriesfollowing the sequence described in a flowchart or a sequence diagram.In one example, the processing steps in each process may be executed ina sequence that differs from a sequence described herein as a flowchartor a sequence diagram, and furthermore may be executed in parallel.

Furthermore, it is also possible to create a computer program forcausing a processor (e.g., CPU or DSP) included in the apparatus (e.g.,the control device or the module thereof, the base station, or the basestation device or the module thereof) according to the presentspecification to function as the component (e.g., the selector, thegrouping unit, the information acquisition unit, and/or the controller)of the apparatus. Furthermore, it is also possible to provide arecording medium having the computer program recorded therein.Furthermore, it is also possible to provide an apparatus (e.g., thecontrol device or the module thereof, the base station, or the basestation device or the module thereof) including a memory having thecomputer program stored therein and one or more processors which canexecute the computer program. Furthermore, a method including theoperations of the components of the apparatus (e.g., the selector, thegrouping unit, the information acquisition unit, and/or the controller)is included in the technology according to the present disclosure.

Furthermore, the effects described in this specification are merelyillustrative or exemplified effects, and are not limitative. In otherwords, In conjunction with or in place of the above effects, thetechnology according to the present disclosure may achieve other effectsthat are clear to those skilled in the art based on the description ofthis specification.

Additionally, the present technology may also be configured as below.

(1)

An apparatus including:

an acquisition unit configured to acquire information indicating one ormore second base stations located within coverage of a first basestation connected to a wired backhaul; and

a controller configured to control establishment of a wireless backhaulbetween the first base station and each of the one or more second basestations.

(2)

The apparatus according to (1), further including:

a selector configured to select the one or more second base stations.

(3)

The apparatus according to (2),

wherein the selector selects the one or more second base stationsdepending on a position and a traffic volume of a terminal deviceconfigured to perform wireless communication with the first basestation.

(4)

The apparatus according to any one of (1) to (3),

wherein the acquisition unit acquires information indicating a pluralityof second base stations located within the coverage, and

the controller controls establishment of a wireless backhaul between thefirst base station and each of the plurality of second base stations.

(5)

The apparatus according to (4), further including:

a grouping unit configured to perform grouping of the plurality ofsecond base stations so that the second base stations capable of havingmutually independent paths in wireless communication with the first basestation are placed in a same group.

(6)

The apparatus according to (5),

wherein the grouping unit performs the grouping of the plurality ofsecond base stations for each of a downlink and an uplink.

(7)

The apparatus according to (5) or (6),

wherein the grouping unit performs the grouping of the plurality ofsecond base stations based on information relating to a position of eachof the plurality of second base stations.

(8)

The apparatus according to any one of (5) to (7),

wherein the grouping unit performs the grouping of the plurality ofsecond base stations based on information relating to traffic of each ofthe plurality of second base stations.

(9)

The apparatus according to any one of (5) to (8),

wherein the grouping unit performs the grouping of the plurality ofsecond base stations based on a result obtained by measurement of areference signal by each of the plurality of second base stations, and

the measurement includes measuring each of different sets of thereference signal.

(10)

The apparatus according to any one of (4) to (9),

wherein the acquisition unit acquires information indicating two or moregroups obtained by grouping the plurality of second base stations, and

the controller allocates a different period for wireless communicationwith the first base station to each of the two or more groups.

(11)

The apparatus according to any one of (4) to (10),

wherein the acquisition unit acquires information indicating a groupobtained by grouping the plurality of second base stations, and

the controller allocates one or more antenna elements among a pluralityof antenna elements of the first base station, to each of the secondbase stations belonging to the group.

(12)

The apparatus according to (11),

wherein the controller allocates the one or more antenna elements toeach of the second base stations belonging to the group based oninformation relating to a direction of arrival of a signal transmittedby each of the second base stations belonging to the group orinformation relating to a quality of a propagation channel between eachof the second base stations belonging to the group and the first basestation.

(13)

The apparatus according to any one of (4) to (12),

wherein the acquisition unit acquires information indicating a groupobtained by grouping the plurality of second base stations, and

the controller selects a multi-antenna communication scheme to beapplied to the group.

(14)

The apparatus according to (13),

wherein the communication scheme is diversity, spatial multiplexing, orbeamforming.

(15)

The apparatus according to (13) or (14),

wherein the communication scheme is single-user multiple-input andmultiple-output (MIMO) or multi-user MIMO.

(16)

The apparatus according to any one of (13) to (15),

wherein the controller selects the communication scheme based on thenumber of the second base stations belonging to the group or informationrelating to a quality of a propagation channel between each of thesecond base stations belonging to the group and the first base station.

(17)

The apparatus according to any one of (1) to (16),

wherein each of the one or more second base stations is not a relaystation but an independent base station, and has own retransmissioncontrol function.

(18)

The apparatus according to any one of (1) to (17),

wherein the one or more other base stations are wireless communicationdevices having a first operation mode for operating as a mobile stationand a second operation mode for operating as a base station.

(19)

The apparatus according to any one of (1) to (18),

wherein the apparatus is the first base station, a base station deviceintended for the first base station, or a module intended for the basestation device, and

the control includes performing a procedure for establishing thewireless backhaul with each of the one or more second base stations.

(20)

The apparatus according to any one of (1) to (18),

wherein the apparatus is a control device for controlling the first basestation or a module intended for the control device,

the control of establishment of the wireless backhaul includes providinginformation for establishing the wireless backhaul for the first basestation, and

the information for establishing the wireless backhaul includesinformation indicating the one or more other base stations.

(21)

A method performed by a processor, the method including:

acquiring information indicating one or more second base stationslocated within coverage of a first base station connected to a wiredbackhaul; and

controlling establishment of a wireless backhaul between the first basestation and each of the one or more second base stations.

(22)

A program causing a processor to execute:

acquiring information indicating one or more second base stationslocated within coverage of a first base station connected to a wiredbackhaul; and

controlling establishment of a wireless backhaul between the first basestation and each of the one or more second base stations.

(23)

A readable storage medium having a program stored therein, the programcausing a processor to execute:

acquiring information indicating one or more second base stationslocated within coverage of a first base station connected to a wiredbackhaul; and

controlling establishment of a wireless backhaul between the first basestation and each of the one or more second base stations.

REFERENCE SIGNS LIST

-   1 system-   10 coverage-   20 second base station-   40 wired backhaul-   100 first base station-   151 selector-   153 grouping unit-   155 information acquisition unit-   157 controller-   200 control device-   231 selector-   233 grouping unit-   235 information acquisition unit-   237 controller

1. An apparatus, comprising: circuitry configured to: acquire firstinformation of at least one of a plurality of second base stations,wherein the first information indicates that the plurality of secondbase stations is within a coverage area of a first base station, andwherein the first base station is connected to a server via a wiredbackhaul; receive a measurement result of a reference signal from eachsecond base station of the plurality of second base stations, whereinthe measurement result includes measured values of different sets of thereference signal; select the plurality of second base stations based onthe measurement result, wherein each second base station of the selectedplurality of second base stations is in wireless communication with thefirst base station via a mutually independent path; and controlestablishment of a wireless backhaul connection between the first basestation and each second base station of the selected plurality of secondbase stations, based on the first information.
 2. The apparatusaccording to claim 1, wherein the circuitry is further configured toselect the at least one of the plurality of second base stations.
 3. Theapparatus according to claim 2, wherein the circuitry is furtherconfigured to select the plurality of second base stations based on aposition of a terminal device and a traffic volume of the terminaldevice, and wherein the terminal device is in wireless communicationwith the first base station.
 4. The apparatus according to claim 1,wherein the circuitry is further configured to select the plurality ofsecond base stations based on a downlink communication and an uplinkcommunication between the first base station and each second basestation of the plurality of second base stations.
 5. The apparatusaccording to claim 1, wherein the circuitry is further configured toselect the plurality of second base stations based on second informationthat indicates a position of each second base station of the pluralityof second base stations.
 6. The apparatus according to claim 1, whereinthe circuitry is further configured to select the plurality of secondbase stations based on third information that indicates a traffic volumeof each second base station of the plurality of second base stations. 7.The apparatus according to claim 1, wherein the circuitry is furtherconfigured to: acquire fourth information that indicates at least two ofa plurality of third base stations; and allocate a different period toeach of the at least two of the plurality of third base stations forwireless communication with the first base station.
 8. The apparatusaccording to claim 1, wherein the circuitry is further configured to:acquire fifth information that corresponds to the selected plurality ofsecond base stations; and allocate at least one unique antenna elementof the first base station to each second base station of the selectedplurality of second base stations.
 9. The apparatus according to claim8, wherein the circuitry is further configured to allocate the at leastone unique antenna element to each second base station of the selectedplurality of second base stations based on one of: a direction ofarrival of a signal transmitted by each second base station of theplurality of second base stations, or a quality of a propagation channelbetween each second base station of the plurality of second basestations and the first base station.
 10. The apparatus according toclaim 1, wherein the circuitry is further configured to select amulti-antenna communication scheme between the selected plurality ofsecond base stations and the first base station.
 11. The apparatusaccording to claim 10, wherein the multi-antenna communication scheme isone of diversity, spatial multiplexing, or beamforming.
 12. Theapparatus according to claim 10, wherein the multi-antenna communicationscheme is one of single-user multiple-input and multiple-output (MIMO)or multi-user MIMO.
 13. The apparatus according to claim 10, wherein thecircuitry is further configured to select the multi-antennacommunication scheme based on one of a number of the selected pluralityof second base stations or a quality of a propagation channel betweeneach second base station of the plurality of second base stations andthe first base station.
 14. The apparatus according to claim 1, whereineach second base station of the plurality of second base stations is anindependent base station that has a retransmission control function. 15.The apparatus according to claim 1, wherein the plurality of second basestations comprises wireless communication devices with a first operationmode to operate as a mobile station and a second operation mode tooperate as a base station.
 16. The apparatus according to claim 1,wherein the apparatus is one of the first base station or at least apart of elements of a base station device for the first base station,and wherein the circuitry is further configured to control theestablishment of the wireless backhaul connection based on a procedureto establish the wireless backhaul connection with each second basestation of the selected plurality of second base stations.
 17. Theapparatus according to claim 1, wherein the apparatus is one of acontrol device or a module of the control device, wherein the controldevice is configured to control the first base station, and wherein thecircuitry is further configured to transmit second information toestablish the wireless backhaul connection for the first base station.18. The apparatus according to claim 1, wherein the first base stationsimultaneously communicates wirelessly with the selected plurality ofsecond base stations in a period allocated to the selected plurality ofsecond base stations, based on a same frequency band.
 19. A method,comprising: acquiring information of at least one of a plurality ofsecond base stations, wherein the information indicates that theplurality of second base stations is within a coverage area of a firstbase station, and wherein the first base station is connected to aserver via a wired backhaul; receiving a measurement result of areference signal from each second base station of the plurality ofsecond base stations, wherein the measurement result includes measuredvalues of different sets of the reference signal; selecting theplurality of second base stations based on the measurement result,wherein each second base station of the selected plurality of secondbase stations is in wireless communication with the first base stationvia a mutually independent path; and controlling establishment of awireless backhaul connection between the first base station and eachsecond base station of the selected plurality of second base stations,based on the information.
 20. A non-transitory computer-readable mediumhaving stored thereon computer-executable instructions which, whenexecuted by a processor, cause the processor to execute operations, theoperations comprising: acquiring information of at least one of aplurality of second base stations, wherein the information indicatesthat the plurality of second base stations is within a coverage area ofa first base station, and wherein the first base station is connected toa server via a wired backhaul; receiving a measurement result of areference signal from each second base station of the plurality ofsecond base stations, wherein the measurement result includes measuredvalues of different sets of the reference signal; selecting theplurality of second base stations based on the measurement result,wherein each second base station of the selected plurality of secondbase stations is in wireless communication with the first base stationvia a mutually independent path; and controlling establishment of awireless backhaul connection between the first base station and each ofthe selected plurality of second base stations, based on theinformation.